Working on the text

Ex.5. Pronounce the words correctly:

unfamiliar, automatically, to explore, whether, influence, various, quantity, value, particular, special, to touch, humidity, scratches, vacuum, outgassing, to determine, principle, collision, conservation, composite, component.

Ex.6. Read and translate the following text:

TEXT

What is mass?

When we push something we are unfamiliar with, such as when we kick an object on the street, we automatically pay attention to the same aspect that children explore when they stand in front of a mirror for the first time, or when they see a red laser spot for the first time. They check whether the unknown entity can be pushed, and they pay attention to how the unknown object moves under their influence. Repeating the experiment with various pairs of objects, we find – as in everyday life – that a fixed quantity mi can be ascribed to every object i.

The more difficult it is to move an object, the higher the quantity is. In order to have mass values that are common to everybody, the mass value for one particular, selected object has to be fixed in advance. This special object is called the standard kilogram and is kept with great care in a glass container in Sevres near Paris. The standard kilogram is touched only once every few years because otherwise dust, humidity, or scratches would change its mass. By the way, the standard kilogram is not kept under vacuum, because this would lead to outgassing and thus to changes in its mass. Through the standard kilogram the value of the mass of every other object in the world is determined.

The mass thus measures the difficulty of getting something moving. High masses are harder to move than low masses. Obviously, only objects have mass but images don’t. (By the way, the word ‘mass’ is derived, via Latin, from the Greek μαζα – bread – or the Hebrew ‘mazza’ – unleavened bread. That is quite a change in meaning.) Experiments with everyday life objects also show that throughout any collision, the sum of all masses is conserved. The principle of conservation of mass was first stated by Antoine-Laurent Lavoisier.

Conservation of mass also implies that the mass of a composite system is the sum of the mass of the components. In short, Galilean mass is a measure for the quantity of matter.

Ex.7. Translate the definitions into Russian. Find in the text terms (nouns) defined by these definitions:

1. a device that makes a very strong beam of controlled light (with rays that are parallel and of the same wavelength);

2. an amount or a number of smth.;

3. a unit for measuring weight equal to 1000 grams;

4. the amount of water in the air; conditions in which the air is very warm and damp;

5. the space that is completely empty of any substances including all air or other gas;

6. the quantity of material that smth. contains;

7. a picture of smb./smth. seen in a mirror, through a camera, or on a television or computer;

8. something made by putting together different parts of materials.

Ex.8. Answer the following questions:

1. What do we automatically pay attention to when we push something we are unfamiliar with, such as when we kick an object on the street?

2. What aspect do children usually explore when they stand in front of a mirror for the first time?

3. What mass value do we call the standard kilogram?

4. Do scientists keep the standard kilogram with great care in a glass container in France or England?

5. Why do specialists touch the standard kilogram only once every few years?

6. Why don’t specialists use vacuum for keeping the standard kilogram?

7. What do specialists determine with the help of the standard kilogram?

8. Are high or low masses harder to move?

9. Images don’t have mass, do they?

10. What do experiments with everyday life objects also show?

Ex.9. Ask general, alternative and disjunctive questions to the following sentences:

1. They automatically pay attention to the same aspect of the problem.

2. The more difficult it is to move an object, the higher the quantity is.

3. The mass measures the difficulty of getting something moving.

4. High masses are harder to move than low masses.

5. Only objects have mass.

6. The mass of a composite system is the sum of the mass of the components.

Ex.11. Retell the text “What is mass?”

Ex.12. Read and translate the following text without using a dictionary:

TEXT